/Engine/Source/Runtime/AudioMixerCore/Public/AudioMixerNullDevice.h
Constructing theFMixerNullCallbackimmediately begins calling InCallback every BufferDuration seconds.
FMixerNullCallback ( float BufferDuration, [TFunction](API\Runtime\Core\GenericPlatform\TFunction)< void()> InCallback, EThreadPriority ThreadPriority, bool bStartedPaused )